The present invention relates to local television transmission and, more particularly, to a wireless local television transmission system comprising, a source of a video signal to be viewed at a remote location; up converter means connected to the source for shifting the video signal to a frequency above the normal television bands; transmitter means connected to the up converter means for transmitting the video signal at the shifted frequency; receiver means at the remote location for receiving the transmitted video signal; down converter means connected to the receiver means for shifting the video signal back to a frequency within the normal television bands and identified with a known channel; and, television set means connected to the down converter for processing and displaying the video signal on the known channel.
Television (TV) is a major factor in everyday life throughout much of the world. Unfortunately, the rapid advances in the art relative to devices for producing the television signals that drive the TV sets has not provided a convenient method of connecting those devices. All this is to say that television technology quickly outstripped interconnecting technology resulting, quite literally, in a mess. The typical home has at least one video cassette recorder (VCR) and, probably, two TV sets. Cable has generally replaced the old antenna on the roof; so, there is probably a cable select box as well. All these are usually interconnected with so-called co-axial cable or "co-ax". The co-ax is stiff and cumbersome. If the viewer wants to have the ability to watch one station while recording another, quite often a so-called "A-B switch" must be employed, particularly where scrambled pay channels are being unscrambled within the cable select box. The result is a tangled web of co-axial cable connected between signal splitters, A-B switches, cable select boxes, VCRs and TV sets.
Where it has been desired to have a single VCR and/or cable select box provide signals to TV sets in separated rooms, the co-ax has been run through the walls, attics, along baseboards, or what have you, to make the necessary interconnections. In one recent commercial prior art attempt to overcome the problem, fine double stranded wire has been substituted for the unwieldy co-ax. The use of an ordinary pair of wires in place of the co-ax is also addressed in U.S. Pat. No. 4,054,910 of Chou et al. The patent of Karplus (U.S. Pat. No. 3,093,706) suggests transmitting the TV signal over the power lines. Since the latter patent is over twenty years old and the use of power lines to replace co-ax has not been adopted, it would appear that the teaching did not produce acceptable results.
Some of the basic problems presented and some prior art attempts at their solution are depicted in FIGS. 1-6. The basic problem is depicted in FIG. 1; that is, some one or more TV signal sources 10 (e.g. video camera 12, TV antenna 14, cable select box 16 or VCR 18) must be connected to the TV set 20. The typical method is co-axial cable 22 with signal splitters and A-B switches not shown), as necessary for the particular hook-up. Devices such as the cable select box 16 and VCR 18 typically output their signal at the frequency and in the manner of a normal TV signal from channel 3 or 4 (although other normal channels can be, and have been, used). The input to the TV set 20 is at its normal signal input terminals and the tuner of the set 20 is tuned to the appropriate channel (3, 4, etc.) to receive the signal in the normal manner.
In an effort to eliminate the interconnecting wires, some illegal efforts have been made to wirelessly transmit the combined video/audio signal from the VCR 18 in the manner shown in FIG. 2. This approach is also employed in commercially available devices in Japan (where it is not illegal) employing UHF television channel frequencies. The audio and video signals developed by the VCR 18 from the cassette being played (not shown) are input to a transmitter 24 which is set up to transmit with a low power signal from antenna 26 on a channel normally not used commercially in the local area, such as channel 3 or 4 as mentioned above (with channels 14 and 15 sometimes being used). The TV set 20 then picks up the transmitted signal over its normal "rabbit ears" antenna 28. This, of course, is an illegal transmission at a licensed frequency in the United States and can, and has, gotten the manufacturers and sellers of such devices in serious trouble with the Federal Communications Commission.
One very common prior art arrangement for cutting down on the number of cables and wires required is shown in FIG. 3. The typical VCR 18 has a power outlet (not shown) on the back of the case into which the power cord 30 of the TV set can be plugged instead of having to run two power cords to a wall outlet. Often, the power outlet of the VCR 18 is controlled by the VCR 18 so that to turn on both the VCR 18 and TV set 20, only the VCR 18 needs to be turned on. Commonly, the VCR 18 can be controlled in all its functions by an infra red (IR) transmitting controller 32 which also eliminates wires and cables. The controller 32 emits a coded beam of IR energy 34 which is detected by an IR detector 36 on the front of the VCR 18. Which brings us to the prior art improvement to such systems depicted in FIG. 4. The transmitting controller 32 must be within a limited distance of the detector 36 and must be able to have the IR energy 34 therefrom directed onto the detector 36. Thus, if the VCR 18 and TV set 20 are remotely located from one another, the transmitting controller 32 is useless at the location of the TV set 20 where the viewer is located. To solve this problem, U.S. Pat. No. 4,509,211 of Robbins teaches the use of a transmitter 38 having an IR detector 36' therein which detects the coded beam of IR energy 34 from the transmitting controller 32 and transmits the signal as an electrical signal on the interconnecting co-axial cable 22 between the VCR 18 and TV set 20 to a repeater 40 which uses the electrical signal to produce a duplicate coded beam of IR energy 34' which is directed on the detector 36 of the VCR 18 to operate it remotely.
For the operation of multiple TV sets 20 located throughout a plurality of rooms such as in a hotel or apartment building, the patent of Parker (U.S. Pat. No. 2,628,275) suggests the arrangement shown in simplified form in FIG. 5. A transmitter 42 takes the received TV signals and retransmits them on an antenna wire 44 disposed in the baseboard of the rooms throughout the building. The antenna wire 44 is in lieu of co-axial cable 22 with splitters at each room location and cable 22 piercing the walls at each location to provide connection thereto. Each TV set 20 is provided with an antenna 28' disposed along the baseboard in close spaced relationship to the antenna wire 44 causing the signal in the wire 44 to be inductively coupled into the antenna 28'.
Finally, as depicted in FIG. 6, it is well known to wirelessly transmit the audio portions of the TV signal from an audio transmitter 46 to a local speaker 48 located where the viewer sits to provide privacy in viewing television; that is, one viewing and listening to the TV set 20 by means of the local speaker 46 does not disturb someone else in the room or house. Such devices are exemplified by the patents of Sienkiewicz (U.S. Pat. No. 3,259,689) and Trask (U.S. Pat. No. 4,021,737); the latter patent being directed more to providing high fidelity sound than to privacy.
Wherefore, it is the object of the present invention to provide a method and apparatus for the wireless local broadcasting of video signals in a broad spectrum of applications which eliminates the necessity for any kind of physical interconnections, is legal, and which provides a high quality signal.
It is another object of the present invention to provide a method and apparatus for the wireless local broadcasting of control signals associated with wirelessly broadcast video signals.
It is yet another object of the present invention to provide a method and apparatus for combining control signals for multiple associated video devices into a single device so as to eliminate the necessity of having multiple controllers.
Other objects and benefits of the present invention will become apparent from the description which follows hereinafter taken in combination with the drawing figures which accompany it.